Selective receiving and amplifying circuit



Nov. T7, 1953 NOWAK SELECTIVE RECEIVING AND AMPLIFYING CIRCUIT Filed May 15, 1949 AAAAAAA 3n yg W (Ittorneg Patented Nov. 17, 1953 LVING re atta-i ite; 13, sar 93,022 .izg s zrsaw-2 This invention relates to a device for receiving generative feed back, this coil eissd ws rb a? ptsi isbly I n ar arass.

cuitcoil w common support.

U. s. Patent No. 2,619,588, issued Novemr 2;; 1952, 1 devised circuits ,vrhich permit @Iovirig tthe' selectivity of the receiving pram- ;plifying their essential characteristics QwhichIactsrecipmcaIIy inrelation to the lparallel resonant circuitpf-tlrerece' ingmeans. This deenerative feed more feralilfacts in Opposi- I? np to obtain tior1' tf3 tl ie regenerative lags iliistaiitia'l improvme'" m a v 1-- -4 L, x an. oor rig to the statements made m my er "application. The reci rocarlrct of the opposed. coupling is obtained preferably by connecting the elements which provide the degenerative action in series with a tunable parallel resonant circuit. The effect of the former is opposed to that caused by the regenerative feed back element, in the series circuit, for its impedance is increased for currents of frequencies to which it is tuned.

It was found, by experiment, that the position of the coils relative to each other is of importance. In particular, experiments have shown that the incoming signals should be impressed from the collecting circuit upon the regeneration producing tuned anode circuit of the first stage of the amplifier, rather than upon the coil in its'grid or input circuit.

' The invention is, therefore, particularly concerned with the design of the input stage of the receiver or amplifier. This special design yields the surprising efiect of an improved selectivity, and consequently constitutes an improvement over the invention of the prior application. The explanation of this fact is that, first, the grid of the tube can not be controlled aperiodically, although the circuit connected thereto is, for purposes of economy, an untuned one, while the tuned circuit is inserted in the anode circuit and, second, that undesirable frequencies are eliminated or at least strongly attenuated in response to the reciprocal counter-coupling action.

Acordingly, it is the object of this invention to provide an improved circuit for high selectivity reception of radiated energy in which the energy is first introduced into a parallel tuned circuit in 2 ihgTYthe hutilizationof degenerative ,f'e'edebabk I he vanode circuit of an amplifier rather than to "ico'il'in the grid circuit.

Another nurnqse pi the inven ion is t pres an imp ored ,circ ib 22 1: the leqentiqnans amnt r fication of radio frequency energy with a d enf..s.e ectivity in thetplatfi c r ui Of an amplifier ha gries wit afn all til Ionant circuit and d generation which an input ,co ithatn ay the-A r tes with an antenna is ,couplerirtoiih in qt a d ispqnri sted JQQHCQWQfiQQiL e to 991 the a, 6 2??? coil being connected in series wi th A further object of the invention is to provide a circuit arrangement of the type described in which the grid coil, parallel circuit inductance, the antenna or input coil and the degeneration coil are wound in that order on a common core.

The manner in which these objects are obtained will become apparent from a consideration of the following description in which:

Figure 1 shows a schematic diagram of the circuit that is the subject of this invention, and

Figure 2 shows the relative positions of the various coils in a common core.

In the drawing, Figure 1 shows the circuit in which the coil 2 is included in the grid-cathode circuit of tube 4. This tube may act as radio frequency amplifier or as a detector. The anode path includes in series a condenser 6, coil 8, and the tunable resonant circuit [0 comprised of an inductance l2 and a variable condenser M. The inductance I2 is arranged to produce regenerative feed back, while degenerative feed back is produced by coil 8. Incoming signals are impressed from the collecting or input coil I6 upon both the coils 8 and I2. As coil I6 is interposed between coils 8 and I2, it will be simultaneously afiected by the regenerating action exercised by circuit 10 and the degenerating action of coil 8, and this combined action results in an attenuation of undesirable frequencies. The coil 2 in the grid circuit is energized practically only by coil l2. The result is a high selectivity in addition to good quality of the reception.

The second stage of the amplifier, as shown in the drawing, Figure 1, is capacitively coupled to the first, whereas restistance l8 which may be replaced by a choke provides a filter for radio frequency currents.

, H The tunable parallel resonant circuit l preferably has one of its terminals directly connectled to the cathode of tube 2 or electron discharge 'deyide 4'.

Figure 2 illustrates the manner in which the different coils 2, l6, 8 and 12 are mounted on a common support which may be a magnetite core, or the like. The coils are wound and mounted adjacent to each other in the following sequence:

grid coil 2, tunable circuit coil I2, collecting coil' I6, and degenerating coil 8.

Suitable number of turns are:

Turns Coil 2 3 to 15, Coil l2 '7 to 90 Coil 16 to 12 Coil 8 6 to 40 and said cathode, an input coil inductively coupled to each of said other coils and physically placed between them on a common core so that said inductance and said degeneration coil receive substantially all their energy from said input coil, and a grid coil mounted on said core adjacent said inductance in such manner as to receive substantially all its excitation directly from said inductance.

2. A circuit for improving the selectivity of a and cathode so as to supply signals appearing therein to said grid, said grid coil being electromagnetically coupled to said tuned circuit so as to receive substantially all of it energy from said tuned circuit, an input coil, said latter coil being coupled to said tuned circuit and said degenerating coil so that said latter coil and said degeneration coil receive substantially all their energy from said input coil.

Number References Cited in the file of this patent UNITED STATES PATENTS 7 Name Date Landon June 1'7, 1930 Townsend June 2, 1931 Keall May 3, 1938 Kautter June 13, 1939 Farrington 1 Apr. 16, 1940 FOREIGN PATENTS Country Date Great Britain Sept. 25, 1924 Germany May 30, 1940 Switzerland Sept. 1, 1947 Number 

